1. Field of the Invention
The present invention relates to a female terminal provided with an elastic contact piece within a square cylindrical electric contact portion.
2. Description of the Related Art
An example of the female terminal is disclosed in Japanese Published Unexamined Utility Model Application No. 59-84773. This prior art female terminal is composed of a terminal member formed with an electric contact portion and a wire fastening portion, and an elastic contact piece. The electric contact portion is formed into a square cylindrical shape having an opening into which a mated male terminal is inserted and another opening extending to the wire fastening portion. The elastic contact piece is movably housed within the electric contact portion.
The electric contact portion is formed with a base plate, an opposing plate and both side walls for connecting the base plate and the opposing plate. The middle part of the base plate is cut open so as to form two groove portions extending to a predetermined depth in both the side walls of the electric contact portion. The two grooves formed in the side walls serve as two elastic contact piece support portions for supporting both side ends of the elastic contact piece. In more detail, the elastic contact piece is bent inwardly toward the opposing plate along the longitudinal direction thereof, and further formed with two lug portions at roughly the middle portion thereof so as to be supported by the two groove portions. Therefore, the elastic contact piece is movably housed in the electric contact portion under such conditions that both longitudinal ends of the elastic contact piece are in contact with the inner surfaces of the base plate and further both the lug portions are in contact with two open surfaces in the two grooves in such a way as to be projected from the grooves, respectively. In other words, the elastic contact piece is supported by the elastic contact piece supporting portions in such a way that the longitudinal movement of the elastic contact piece is restricted by the two grooves formed in the two side walls and further the transverse movement thereof is restricted by the two side walls of the electric contact portions.
Therefore, when the male terminal is inserted into the electric contact portion of the female terminal, the elastic contact piece is deformed extending in the longitudinal direction to apply an appropriate contact pressure to the male terminal on the basis of the restitutive force of the elastic contact piece. Accordingly, the male terminal can be supported between the opposing plate and the elastic contact piece to connect both male and female terminals under appropriate mechanical and electrical contact conditions.
In the above-mentioned female terminal, however, the inner and outer dimensions thereof are usually strictly restricted on the basis of the shape and dimensions of the male terminal or according to the terminal mounting positions, it is necessary to reduce the dimension in the width direction of the female terminal as much as possible. In other words, it is not preferable to form the lug portions in such a way as to project sufficiently outside from the two side walls or to increase the wall thickness of the elastic contact piece. However, when the lug portions are reduced in shape, there exists a problem in that whenever the elastic contact portion is moved slightly in the width direction, any one of the lug portions is dislocated from the elastic contact piece supporting portion toward the opposing plate, so that the elastic contact piece is supported obliquely within the electric contact portion.
In case the lug portion of the elastic contact piece is dislocated from the elastic contact piece supporting portion and thereby inclined, since the male terminal cannot be inserted into the female terminal by the presence of the inclined elastic contact piece, the terminal work is complicated and thereby the terminal workability is deteriorated. In addition, when the male terminal is inserted under the condition that the elastic contact piece is inclined, since the male terminal is brought into contact with the inclined elastic contact piece, an appropriate contact force and a sufficient contact surface cannot be both obtained, thus deteriorating the electric contact condition between both the male and female terminals.